Genetic Relatedness of Salmonella Isolates from Nondomestic Birds in Southeastern United States

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Abstract
Salmonella infections have been implicated in large-scale die-offs of wild birds in the United States. Although we know quite a bit about the epidemiology of Salmonellainfection among domestic fowl, we know little about the incidence, epidemiology, and genetic relatedness of salmonellae in nondomestic birds. To gain further insight into salmonellae in these hosts, 22Salmonella isolates from diseased nondomestic birds were screened for the presence of virulence and antibiotic resistance-associated genes and compared genetically using pulsed-field gel electrophoresis (PFGE) and random amplified polymorphic DNA analysis. Of the 22 Salmonella isolates examined, 15 were positive for the invasion gene invA and the virulence plasmid-associated genes spvC and pef. Most (15 of 22) were generally sensitive to antibiotics. However, twoSalmonella isolates from pet birds were identified asSalmonella enterica serovar Typhimurium DT104. Despite the general susceptibility of these Salmonella isolates to most antimicrobial agents, antibiotic resistance-associated genesintI1, merA, and aadA1 were identified in a number of these isolates. Five distinctXbaI and nine distinct BlnI DNA patterns were observed for the 22 Salmonella isolates typed by PFGE. PFGE analysis determined that Salmonella isolates from passerines in Georgia and Wyoming were genetically related.